Morphology-Controlled Fabrication of Large-Scale Dendritic Silver Nanostructures for Catalysis and SERS Applications

Zi-Qiang Cheng,Zong-Lin Li,Rui Yao,Xin Luo,Shan Liang,Zhi-Wen Li,Yan-Hong Zhou,Guang-Ling Cheng,Jing-Han Xu,Jiang Zhong

doi:10.1186/s11671-019-2923-0

Abstract

Highly branched metallic nanostructures, which possess a large amount of catalyst active sites and surface-enhanced Raman scattering (SERS) hot spots owing to their large surface areas, multi-level branches, corners, and edges, have shown potential in various applications including catalysis and SERS. In this study, well-defined dendritic silver (Ag) nanostructures were prepared by a facile and controllable electrochemical deposition strategy. The morphology of Ag nanostructures is controlled by regulating electrodeposition time and concentration of AgNO3 in the electrolyte solution. Compared to conventional Ag nanoparticle films, dendritic Ag nanostructures exhibited larger SERS enhancement ascribed to the numerous hot spots exist in the nanogaps of parallel and vertically stacked multilayer Ag dendrites. In addition, the prepared dendritic Ag nanostructures show 3.2-fold higher catalytic activity towards the reduction of 4-nitrophenol (4-NP) by NaBH4 than the Ag nanoparticle films. The results indicate that the dendritic Ag nanostructures represent a unique bifunctional nanostructure that serves as both efficient catalysts and excellent SERS substrates, which may be further employed as a nanoreactor for in situ investigation and real-time monitoring of catalytic reactions by SERS technique.

Highlights

Noble metal micro/nanostructures have attracted great attention due to their potential applications in optics [1], catalysis [2–4], surface-enhanced Raman scattering (SERS) [5–7], and solar energy harvesting [8]
Under four AgNO3 concentrations (0.5, 1, 2, and 4 g/L), four morphologies such as meatball-like nanoparticles (Fig. 1a), leaf-like rods (Fig. 1b), highly branched dendrites (Fig. 1c), and micro-hemispheres (Fig. 1d) were obtained. These results indicated the critical role of a proper concentration of AgNO3 in the formation of dendritic Ag fractal nanostructures
Scanning electron microscope (SEM) images of the Ag micro/nanostructures formed after different deposition time were used to investigate the formation process of dendritic Ag fractal nanostructures

Summary

Introduction

Noble metal micro/nanostructures have attracted great attention due to their potential applications in optics [1], catalysis [2–4], surface-enhanced Raman scattering (SERS) [5–7], and solar energy harvesting [8]. Dendritic fractal nanostructures on indium tin oxide (ITO) glass substrates were fabricated by a facile and controllable electrochemical deposition strategy. Fabrication of Dendritic Ag Fractal Nanostructures and Effect of Reaction Conditions The electrochemical deposition method has been described as a facile and effective strategy for shape-controlled synthesis of metal micro/nanostructures due to flexible reaction conditions [7, 18, 25].

Results

Conclusion